package/libevas-generic-loaders: bump to version 1.15.0

Use the newly added libefl package wich provide a new version
of libeina.

Also, update the upstream url and add a hash file.

Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>